In recent years, wire saws have been used to slice workpieces, such as semiconductor materials, magnetic materials, and ceramic, in production processes of semiconductor wafers, solar cells for a solar battery, etc.
The wire saw is an apparatus for slicing a workpiece by imparting reciprocating motion to a wire, and pressing the workpiece against the wire while supplying slurry into which free abrasive grains, such as silicon carbide grains, are blended. The slurry may contain either an oil coolant or a water-soluble coolant, and the water-soluble coolant has recently become mainstream from the viewpoint of an environmental load, such as recycling and drain disposal after use.
It is known that such a slicing process of a workpiece with a wire saw produces swarf, which becomes a material loss (a kerf loss), with a width corresponding to the sum of a wire diameter and about two to three times an abrasive grain diameter, and thinned wires or abrasive grains having smaller diameter are accordingly used to reduce the kerf loss (See Patent Document 1, for example).
In general, the size of an abrasive grain is often represented by a grain size, and the classification thereof is defined in R6001 of Japanese Industrial Standards (JIS), for example.
Conventional slicing processes of semiconductor silicon wafers employed 0.16-mm-diameter piano wires and slurry into which silicon carbide abrasive grains whose the diameter at a cumulative height of 50% is 11.5 μm (also referred to as a grain diameter), #1000-size abrasive grains, are blended, for example. In recent years, however, thinning of wires and shrinking of abrasive grains have been advanced to reduce the kerf loss so that piano wires with a diameter of 0.14 mm and slurry into which silicon carbide abrasive grains whose the grain diameter is 8.0 μm are blended (abrasive grain size #1500) are used.